1. Field of the Invention
This invention relates generally to fastener driving devices and particularly to automatic nailing apparatus for driving successive feeding nails from a nail magazine.
2. Prior Art
One example of a conventional fastener driving device is shown in U.S. Pat. No. 3,708,095. The technique disclosed in this patent requires relatively complex structures, and brings about disadvantages as follows. Firstly, since a percussion rod has four square convex portions, a nosepiece for the sliding of the percussion rod is required to be formed of two members due to the difficulty of manufacturing thereof. Meanwhile, the percussion rod is generally made of a round bar because the percussion rod is screwed into a piston. Therefore, the percussion rod having the four square convex portions and one square concave portion is difficult to manufacture. Secondly, since the nail head of the forefront nail of successive feeding nails contacts or hits against only one flat wall surface of a convex portion between two grooves of the channel portion, the nail head is not always placed at a desired position. Therefore, the positioning of the nail head is unstable. Thirdly, the maximum width of the lower end surface of the percussion rod in the alignment direction of the successive feeding nails is narrower than the maximum width of the nail head in the same direction, and the point of application when the nail is driven by the percussion rod does not exist on the center axis of the nail shank. Therefore, the nails are apt to be driven with an incline. Fourthly, since the contact area between the lower end surface of the percussion rod and the top surface of the nail head is narrow, the lower surface of the percussion rod is apt to abrade.